Resources

History of California's Ambient Air Quality Standards

This page reviewed November 24, 2009.

The following chronology shows when California State agencies took major
actions on ambient air quality standards. Starting in 1969, actions listed were taken by the Air Resources
Board (ARB). Note: After each pollutant, the allowable level and duration are shown in parentheses.

Abbreviations are as follows:

AQS

=

Air Quality Standard

CO

=

Carbon Monoxide

PM

=

Particulate Matter

NO2

=

Nitrogen Dioxide

SO2

=

Sulfur Dioxide

H2S

=

Hydrogen Sulfide

µg/m3

=

Micrograms Per Cubic Meter

1955

Los Angeles County Air Pollution Control District establishes an air pollution
alert system to prevent disaster.

First Alert Levels

Ozone (0.5 ppm)

NOx (3 ppm)

SOx (3 ppm)

CO (100 ppm)

1959

The first statewide air quality standards were set by the Department of
Public Health for total suspended particulates, photochemical oxidants, sulfur dioxide, nitrogen dioxide, and carbon
monoxide.

The table of standards includes notes regarding health and welfare effects
from exposure to ozone, NO2, hydrocarbons, lead, photochemical aerosols, sulfuric acid, and ethylene. The table
also states that carcinogens (e.g., polycyclic aromatic hydrocarbons, arsenic, chromium) should be "as low
as possible."

1962

Ethylene (0.1 ppm, 8 hr and 0.5 ppm, 1 hr)

H2S (0.1 ppm, 1 hr)

NO2 (0.25 ppm, 1 hr - Adverse Level)

The table of standards is revised to include a note regarding health and
welfare effects from exposure to hydrogen fluoride.

1967

California Air Resources Board created. Subsequent AQS are set by ARB.

1969

Air quality standards are set by the ARB for total suspended particulates,
photochemical oxidants, sulfur dioxide, nitrogen dioxide, and carbon monoxide.